Gas turbine engines operate to produce mechanical work or thrust. Specifically, land-based gas turbine engines typically have a generator coupled thereto for the purposes of generating electricity. A gas turbine engine comprises an inlet that directs air to a compressor section, which has stages of rotating compressor blades. As the air passes through the compressor, the pressure of the air increases. The compressed air is then directed into one or more combustors where fuel is injected into the compressed air and the mixture is ignited. The hot combustion gases are then directed from the combustion section to a turbine section by a transition duct. The hot combustion gases cause the stages of the turbine to rotate, which in turn, causes the compressor to rotate.
The air and hot combustion gases are directed through a turbine section by turbine blades and vanes. These blades and vanes are subject to extremely high operating temperatures, often times upwards of 2800 deg. F. These temperatures often exceed the material capability from which the blades and vanes are made. Extreme temps also cause thermal growth in the component, which if not permitted, causes thermal stresses and can lead to cracking. In order to lower the effective operating temperature, the blades and vanes are cooled, often with air or steam. However, the cooling must occur in an effective way so as to use the cooling fluid efficiently.